Vegetable oils



May 31, 1949. F. J. EWING Re. 23,118

PROCESS FOR REFINING ANIMAL AND. VEGETABLE OILS Original Filed May 19, 1959 Reiiucd May 31, 1949 Re. I 23,118

PROCESS FOR REFININGy ANIMAL AND VEGETABLE OILS Frederick J. Ewing, Arcadia, Calif., assig'nor, by mesne assignments, to Benjamin Clayton, Houston, Tex., doing business as Reiining, Un-

incorporated Original No. 2,288,441, dated Jifne 30, 1942, Serial No. 274,649, May 19, 1939. Application for reissue September 17, 1948, Serial No. 49,761

19 Claims.

This invention relates to an improvement in refining of glyceride oils and fats and, more particularly, to the refining of fatty oils in the presence of a diluent.

The refining of fatty oils may comprise the removal of minor impurities, such as gums, phosphatides, and the like, the neutralization and removal of acidic materials, such as free fatty acids and acidic color bodies, the adsorption or bleaching of color bodies in general, and the removal of high melting point constituents. In rening, it is desirable from thestandpoints of cost and quality that the separation of impurities be highly selective in character so that the impurities may be removed without substantial loss of good oil, and it is also desirable that the consumption of refining agents be reduced to a minimum.

It is a general object of the invention to provide an improved refining process of high selectivity, whereby impurities may be very substantially removed with little or no loss of good oil, and also to provide a process in which reagent consumption may be substantially minimized or, Vin some instances, completely avoided.

In accordance with this invention, these and other objects are achieved by refining the oil in the presence of a solvent-diluent having a selective or preferential 'solvent power for the good oil and having relatively little solvent power for the constituents or impurities which it is desired to remove, or for the modications thereof which may be formed in the refining process. 1 have found that' liquefiable, normally gaseous hydrocarbons, e. g., propane, are very excellent selective diluents in this capacity.

The above-mentioned minor impurities contained in the oil may comprise various materials which may be dissolved, or colloidally or -mechanically suspended in the oil, e. g., fragments of seed meall or connective tissue, resins, gums, phosphatides such as lecithin, and similar materials. These materials are usually referred to in the art as gums or gummy materials, and the latter term is employed in the claims as being gener-ic to the resins, phosphatides, etc., found in the crude fatty material. In conventional practice, such materials may be removed together with the fatty acids in an alkali-refining step, or they may be separately7 removed in an initial refining step in which they are flocculated or (Cl. 26o-428.5)

, 2 y advantageous to remove them separately from the fatty acids, and this also results in the prol duction of purer foots or soapstock during subsequent alkali refining. The necessity of employing a separate reagent for this step imposes extra costs on therefining process, however, and,` in addition, there is an entrainment loss of good oil sufferedl during the precipitation of the minor impurities. Furthermore, the value ofthe precipitated impurities as by-products is frequently diminished by the deleterious action thereon of the precipitating reagent.

I have discovered that, upon diluting the crude oil with a liqueiable, normally gaseous hydrocarbon such as propane, the minor impurities are largely or even completely rejected by virtue of the selective action of the diluent, to form a precipitate which settles very rapidly from the fluiddilute oil. By washing the precipitate 4with a further portion of propane, for example, it may be obtained practically free from entrained oil and in a substantially unaltered form highly advantageous for working up into by-products. If desired, the precipitation may be hastened by the addition of a little water to hydrate the.

impurities but, in at least most instances, I find it unnecessary to add any precipitative reagent.

It is an object of my invention to provide a process for refining crude fatty oils and like materials by commingling therewith a selective diluent adapted to dissolve the oil and to precipitate minor impurities such as gums, phosphatides, and the like, more particularly with a diluent comprising liqueable, normally gaseous hydrocarbons such as propane.

The removal of color bodies and adsorbable impurities is frequently accomplished by contacting the oil with an adsorptive agent such as fullers earth or clay. The refining loss of good oil suffered in such a step is relatively high due to retention of oil in the pores of the clay. Furthermore, the adsorption of the color bodies is rarely complete, and, to obtain the desired reduction in color, it is frequently necessary to employ a relatively large proportion of clay which very substantially increases the cost of such refining, both as regards the clay and the refining loss of good oil.

I have found that the selectivity of the adsorbent is greatly increased when the oil is.' diluted with a diluent whereby the oil may be more effectively bleached with a smaller amount of clay, or a given amount of clay may be eRective on a larger proportion of oil, and whereby ing point constituents from the fat or fatty oil.

Such a removal may be desirable where a separation of the constituents for their various utilities is advantageous, or when it is desired to produce a fatty oil which will remain clear and fluid at low storage temperatures. The' latter aspect may be illustrated with reference to the production from cottonseed oil of a wintered salad oil which will not cloud or congeal when stored atlow temperatures, e. g., thoseof a domestic refrigerator.

In conventional practice, the oil is wintered by chilling it to a low temperature at which there is substantial separation of solid s-tearins, and filtering it at this low temperature to separate' vthe solidified higher melting point constituents. Various diiculties in this process are the expense and difiiculty of chilling the oil with an external refrigerant, the high viscosity of the chilled mixture which makes filtration dimcult, and the absence of sharp separation due to occlusion, mutual solubility, and other effects between the liquid and solid phases, which greatly decrease the yield or minimize the melting point differential between the solid and liquid fractions obtained, or both.

I have' discovered that, in the presence of a diluent, the separation of low and high melting point constituents may be made much more selective, resulting in higher yields and greater melting point differentials between the products, and the process of filtration orother separative expedient is also greatly facilitateddue to diminished viscosity, and to changes in the type of filter cake formed. I have found the use of such selective diluents as the liqueable, normally gaseous hydrocarbons is particularly advantageous in the above capacity, and they moreover display a very considerable further advantage in that they make possible a simple and inexpensive chilling process in which the oil-hydrocarbon mixture is internally refrigerated by refrigerative evaporation of the diluent.

It is a'further object of my .invention to provide a process for refining of fatty oils in whichhigher melting point constituents are separated in the presence'of a diluent, particularly a selective diluent such as propane or other liqueable, normally gaseous hydrocarbons, and in which, if desired, the mixture may be chilled to the desired separation temperature by refrigerative evaporation of the diluent.

Other refining steps, such fas the removal of free fatty' acids, e, g., by 'contacting with an aqueous solution of an alkali, chemical bleaching, for example, by contacting with alkali or peroxide, and similar rening steps, may also be very advantageously practiced in the presence of a, diluent, particularly one having selective properties, such as propane or other liqueable, normally gaseous hydrocarbons. It is distinctly advantageous, therefore, to maintain the fatty oil in solution in the selective diluent throughout all of such refining steps as it may be necessary to employ to produce the desired refined product.

It is an object of the present invention to provide a refining process in which the crude fatty oil is initially commingled with a diluent, particularly a liqueable, normally gaseous hydrocarbon diluent, and the oil maintained in association with more or less of'saiddiluent throughout the entire refining procedure necessary to produce the desired rened product or products, more particularly where such procedure comprises one or more of the following steps: (a) removing minor impurities rejected by such dilution; (b) contacting the oil with an alkaline refining agent; (c) contacting the oil with an adsorptive refining agent; (d) internal or evaporative refrigeration of the solution; and (e) separation of higher melting point constituents.

Further objects and aspects of the invention will become apparent in the following discussion of the flow diagram shown in the drawing.

Referring to the drawing, there is there-illustrated a flow diagram for the refining of fatty oils in the presence of a diluent such as propane. ,Storage vessels I0, II, I2, and I3 are shown for the respective storage of fatty oil, diluent (typically propane), precipitating agent for minor impurities, and alkaline solution for removal of fatty acids. The ow diagram illustrates schematically the equipment generally indicated by the numeral I4 for the removal of minor impurities, the equipment generally indicated by the numeral I5 for chilling, equipment generally indicated by the numeral I6 for the removal of higher melting point constituents, equipment generally indicated by the numeral I1 for alkali-rei'lning and the removal of free fatty acids as foots, equipment generally indicated-by the numeral I8 for refining with an adsorptive reagent, and

evaporating equipment generally indicated by the numeral I9 for theremoval of the diluent from the rened oil.

To follow vthe process in greater detail, crude oil is taken fromthe tank IIJ and transferred by means of a pump 20 through a line 2I and a heat interchangerr 22 to a juncture 23, at which point it is commingled with propane. The propane is brought to the juncture 23 by means of a pump 2l taking suction on the propane stored in the tank I I and transferring it through a line 25 and a heat inter-changer 26 to the juncture 23. The commingledv streams of propane and crude oil flow through a line 34 and a heat interchanger 35 to a decanting vessel 36. Minor impurities which have been rejected or precipitated by the action of the propane on the oil are settled in the decanter 36, and the clear oil-propane solution is removed through a pipe 31. A bafe 38 may be provided, if desired, to prevent short-circuiting of the flow through the decanter.

Provision is made for the addition of water or precipitating agent ahead of the decanting vessel in such instances as this may be deemed advisable, such provision comprising a pump 39 taking suction on the water or solution in the tank I2 and causing it to flow through a, pipe 4D and through a valve 4I into the line 34.

The impurities settling to the bottom of the decanter 36 may -be suitably removed therefrom by means of a screw -conveyor 42 or other means, operating either/continuously or intermittently. The solids or slurry removed by the conveyor 42 will normally contain more or less entrained propane-oil vsolution and, in order to recover the oil content,A provision is made for washing this transferred by the conveyor 42 into a decanter 4I. The precipitates settle to the bottom of the decanter 45, and the clarified wash liquor is removed by means of a line 46 and a pump 41 and returned to the main liquid flow, suitably at the juncture 28.

The oil content of the solids settling to the bottom of the decanter will have been very substantially reduced by the action of the wash propane, and this material may be worked up either continuously or intermittently for recovery of the diluent and production of diluentfree gums, phophatdes, or other minor impurities. The washed impurities are removed from the decanter 45 through a valve 48 and transferred by means of a conveyor 49 which may be provided in part with a heating jacket 58 into an evaporator 5I. The heat imparted by means of the jacket 59 and further heat which may be imparted, if desired, by means of the heating coil 52 positioned in the evaporator 5I, serves to volatilize the propane contained in or associated with the precipitated impurities.l The propane vapors are taken overhead through a line 53 and are condensed in a condenser 54, and the liquid propane condensate is returned by means of a line 55 to a diluent recovery manifold 56. From this manifold, the condensate ows through a y separator 51 adapted to remove any water present in the condensate, and is then returned to the propane storage tank Il. The minor impurities substantially free of the propane 0r other diluent employed are removed from the evaporator 5| by means of a valve 58 and a screw conveyor 59, and constitute one of the products of my process. It is sometimes advantageous to maintain reduced pressures in the evaporator 5l to permit the complete volatilization of the diluent at relatively low temperatures, and for this purpose a pump 68 is shown associated with the line 53. To permit the production of relatively low pressures in the evaporator 5l, the valves I48 and 58 may be closed during the period the pump 69 is in operation, thereby providing for the semi-continuous recovery of the diluent from the minor impurities. However, the valves 48 and 58 become unnecessary if self-sealing conveyors are used for the conveyors 49 and 59, and Continous or intermittent operation can be employed as desired.

The propane-oil solution withdrawn through v the line 31, which solution has been substantially v freed from minor impurities, is introduced into aline 10 for transfer to subsequent processing steps. In instances where the oil is substantially free initially from minor impurities, or where it is not deemed necessary to separate the impurities in an initial step, the mixture of propane and oil formed at the juncture 23 may be introduced into the transfer line 10 by means of a line 1I, which then serves as a by-pass for the equipment i4. From the line 1li, I have provided several alternatives in flow to permit the omission of one or more subsequent refining steps when such steps are deemed unnecessary and/or to change the sequence of subsequent steps to permit the adoption of a rening procedure most suited for the oil being treated and the desired character of the products. In the following discussion, it will be assumed 'that the oil is best refined by sequential application of alkali-refning, clay treatment, and wintering.

The propane-oil solution is transferred from the line 19 through the line 1Ia by means of a valve 12, and introduced into the alkali-refining equipment l1 through a valve 13 and a line 14.

The propane-oil solution flowing through the line 14 is brought to appropriate temperature inl a heat exchanger 15 and commingled with a properly-proportioned solution of aqueous alkali at a juncture 16 to which the propane-oil solution is delivered by a pump 16a. The aqueous alkali is brought to this juncture 16 `from the alkali storage tank I3 by means of a pump 11, a line 18, and a heat interchanger 19 in which the caustic solution is brought to the desired tem perature. Suiiicient mixing can be eilected by bringing -the streams vtogether at right angles at the juncture 16, but, if desired, the commingled streams of caustic and propane-oil solution can be passed through a mixing device 89 which may be of any suitable type, for-example a mixer constructed with a series of orifice plates through lwhich the commingled streams are forced by the action of the proportioning pumps 16a and 11. The mixture is then passed through a conditioning coil 82 in which the temperature may be further modified, if desired.

The resulting stream is then passed through a line 83 into a decanter 84 in which the Toots formed by the action of the alkali on the free fatty acids in the oil are caused to settle. The clarified and puried propane-oil solution is removed from the decanter 84 by means of a pipe B5, and the foots which collect at the bottom of the decanter 84 are removed therefrom, either continuously or intermittently, by means such as a screw conveyor 86. To recover any oil which may be entrained as propane-oil solution in the foots, Wash propane is introduced into the conveyor 86 from the propane supply line 25 by means of a valve 81 and a line 81a. The temperature of the wash propane may be suitably adjusted by means of a heat interchanger 88. The mixture of wash propane and foots formed in the conveyor 86 is fed into a decanter 89 in which the foots are allowed to settle and from which the .wash liquor containing the major portion of the entrained oil is removed by means of a line 88a and pumpb. This wash liquid may be advantageously recycled by return to the line 14, as indicated.

The washed foots are removed from the bottom of the decanter 89 by means of a screw conveyor 88 which is provided, in part at least, With in the evapora-tor 92 may be considerably facilitated by reducing the pressure therein, for which purpose a pump 91 is shown associated with the vapor line 94. The reduction of pressure in the evaporator 92 may be accomplished Without difficulty Where the conveyor is of the selfsealing type adapted to hermetically seal the sans evaporator 92 from the decanter 69, and where a conveyor 98 of the same general type is provided at the bottom of the evaporator 92 for removal of the diluent-free foots therefrom. It is sometimes advantageous, however, t9 provide valves 99 and |00 at the bottom of the decanter 89 and the evaporator 92, respectively, in order to facilitate sealing of the latter when reduced pressures are employed during volatilization of the diluent. y

The foots removed by means of the conveyor 96 are substantially free from oil and diluent and may be further handled as desired. In some instances, I ilnd it advisable to employ suiciently high temperatures and low4 pressures in the evaporator 92 that the water content of the foots is substantially reduced, whereby` a partially del hydrated or completely dehydrated product may be obtained.

The alkali-refined propane-oil solution withdrawn through the line 85 is transferred through a valve to a line and thence through a heat interchanger lI I Ia and to the clay reiining unit I8. This unit comprises a vertical vessel '||2 filled with a charge of granular clay or fullers earth ||3, which clay is supported on a -perforated platel ||4 preferably provided on its upper surface with a blanket of mineral wool |I5. The propane-oil solution is introduced at the top of the vessel I I2 through the line and percolates downwardly through the granular mass of clay ||3 and is withdrawn from the bottom of the vessel by means of a pipe ||6. The clay-treated propane-oil solution withdrawn through the pipe ||6 is conducted through a valve ||1 into a line ||8 and thence through a valve I I9 into a manifold |20 of the chilling apparatus. I5.

The chilling apparatus comprises two vessels |2| 4and |22 into which the propane-oil solution in the line may be alternately introduced by a valve |23 and a valve |24, respectively. The vessel |2| is provided with a vapor line |25 having a valve |26 and connecting into a vapor manifold |21. The vessel |22 is provided with a vapor line |28 having a valve |29 and likewise leading into the vapor manifold |21. This Vapor manifold line |21 is provided with a pump |30 and a condenser |3|, and a line |32 is provided for return of condensate from the condenser to the diluent recovery manifold 56. The

vessel |2| is provided at the bottom with a liquidv Withdrawal line |33 having a valve |34, and the vessel |22 is provided with a similar Withdrawal line` |35 having a v`alve |36, both of these withdrawal vlines being manifolded in a common manifoldline 31 which is connected by a pump |38 with a lter |39.

When the vessel |2| is partially filled with propane-oil solution from the line |20, the valve |23 is closed and the valve |24 is opened, thereby beginning the charge of the vessel |22. While the vessel |22 is being filled, propane is evaporated from the contents of the vessel 2| by opening the valve |26 and starting the pump |30. This evaporation is continued until the abstraction of the latent heat of vaporization of propane from the contents of the vessel |2| has reduced the temperature therein to a' predetermined value. At this low temperature, the higher melting point constituents, or such portion of them as it is desired to separate, will have crystallized from the propane-oil solution sc that the contents of the vessel represent a thin slurry of solid stearin or similar material suspended in the stituents are withdrawn by means of a line |40.

As soon as the vessel |2| is emptied of its low temperature slurry, it is started again on the charging phase of its cycle. A similar cycle of charging, chilling, and `withdrawing is employed with the vessel |22.

When a suicient cake of solids is built up in the lter |39, the flow of low temperature slurry therethrough is temporarily stopped, and Wash propane from the line 25 is transferred through a line I4I, brought to the proper temperature in the heat exchanger |42, and passed through the iilter |39 to wash the cake free from any residual oil. The propane wash is withdrawn through the line |40. When the filter cake is sufiiciently Washed, it is caused to separate from the filter leaves, for example by applying a slight back pressure to the iilter, and to fall into a hopper |43 associated with the lter |39. From the hopper |43, the solid constituents are conveyed by means of a screw conveyor |44, which may be provided with a heating jacket |45, into an evaporating vessel |46 equipped with a. heating coil |41. The stearins and other solids are heated suiiiciently in the evaporator |46 to volatilize any diluent associated therewith, and are preferably heated to such *a temperature that they are melted and reduced to a uid condition. The vapors are removed through a line |48 leading into a vapor manifold 149 in which they are transferred to a condenser |50 arranged to return condensate to the diluent recovery line 56. A pump |5| is associated with the vapor manifold |49 whereby the evaporation may be carried out at diminished pressures'if desired. The melted stearins free from dissolved diluent are removed from the evaporator |46 by means of a line |52 and a pump |53 and represent one of the productsof my process.

The ltrate and wash liquor from the lter |39, which are Withdrawn through the line |40, are transferred into a manifold line |54 and, passing through a valve |55, are introduced into the evaporator I9. This evaporator comprises a closed tank |56 having a heating coil |51 and a vapor line |58 leading into the vapor manifold |49. The refined wintered oil is freed from the solvent or diluent associated therewith in the evaporator I9, suitable conditions of temperature and pressure being maintained therein for the substantially complete removal of the solvent or diluent by appropriate adjustment of the heat imparted to the oil by the heating coil |51 and of the pressure on the oil by adjustment of the pump |5|. The refined oil free from diluent is removed from the evaporator I9 by means of a line |60 and a pump |6I, and constitutes the chief product of my process.

When degumming is the only refining step which it is desired to employ. the propane-oil solution in the transfer line 10 may be brought directly to the evaporator I9 by means of valves 200 and 20|. a pipe 202, and a pipe 203. When it is desired to remove the stearins or other high melting point constituents without employing the alkalirening and clay treating steps, the

kpropane-oil solution in the line 10 may be ini'- tially brought into the chilling equipment I5 -by and -the contents of sans penin the valve 200, the valves 12, IIS, and 201 being losed. When it is desired to clay treat the propane-oil solution before the step of alkalireiining, the valve 13 inthe line Ha is closed the line Ha diverted through a line 200 and a valve 205 into the line III. The valve |I1 on the withdrawal line lli from the clay treater I0 is then likewise closed, and the clay-treated propane-oil solution is transferred by means of a valve 20E and a line 201 leading to and connecting with the pipe 1l, whereafter the propane-oil Vsolution may be alkali-refined. Or, if desired, the alkali-reiining step may be omitted by closing the valve 206 and opening the valve I I1, thus sending the oil to the chilling equipment I5 or evaporating equipment I9, as may be desired. Or, in those instances where it is desired to alkali-treat without claytreatlng, the clay treater IB may bev by-passed by means of a valved by-pass line 208. A valved by-pass line 209 has also been provided between line IIB and line 203 for by-passing the alkali and/0r clay-treated propane-oil solution directly to evaporator I9 when it is 'not desired to 4prac- I tice the step of wintering.

The removal of higher melting point constituents may also serve as a step preliminary to the steps of alkali-refining and/or clay-treating, in which case the low temperature filtrate in manifold lil is diverted from its flow toward evaporator i0 by closing valve |55 and opening valve 2 I0 in a transfer line 2li leading from the manifold line |54 to the line Tia.

My process, as described, is dependent upon the use cf suitable diluents and, as I have indicated, I have found that the liquefied, normally gaseous hydrocarbons are particularly advantageous diluents. By the term "liquefied, normally gaseous hydrocarbons, I have particular reference to such hydrocarbons as propane and butane, which may be liqueiied at atmospheric temperatures Without the necessity of imposing unduly high pressures thereon. Where reference is made to propane or any other individual hydrocarbon, I do not mean to imply that I employ the pure hydrocarbon exclusively, but I employ the terms in their commercial significance to indicate a propane cut or a butane cut such as may be taken from suitable plates in a refinery stabilization column. A propane cut, for example, will consist largely of propane, together with some butane, and will have minor proportions of lighter materials, such as methane and ethane, and also minor proportions of heavier materials such as pentane.y Such a cut is gaseous at ordinary temperatures and pressures but may be liqueed by the imposition of several atmospheres pressure.

Among the advantages resulting from the employment of liqueed, normally gaseous hydrocarbons as dlluents are the ease of removal of the diluents from the finished product at relatively low temperatures not injurious to the product, the ease of obtaining lowprocessing temperatures by refrigerative evaporation of the diluent, the greatly reduced viscosity and density obtainable by blending these very light hydrocarbons with the oil, whereby processes such as ltration and settling are greatly facilitated, the latter to such a marked extent that simple decantatlon vessels may be used, iftdesired, to provide a continuous means for separation of the impurities from the oil-propane mixture, and' the highly selective character of the diluent, which in each renning step serves to reduce the loss-oi goed oil, to increase the degree to whichI impurities are removed when the oil is refined, and to reduce the quantity of refining agent, if any, necessary for the removal of such impurities.

The highly selective character of the liqueiiable. normallygaseous'hydrocarbon serves to improve the emciency of each refining step. In degumming, there is in most instances a rejection or precipitation of the minor impurities arising solely from the selective action of the propane or similar diluent, and, in other instances, such impurities are brought to the point of incipient precipitation whereby they are very readily removed by the hydrating action of a little water or the precipitating action of a small amount of precipitating agent, e. g., an aqueous solution of an electrolyte. In the step of alkali-refining, one important feature attributableto the selectivity of the diluent is the production of a neutralized oil substantially free from any dissolved soap.

Propane and other normally gaseous. liquefiable -hydrocarbons have substantially no solvent power color bodies, thereby giving an alkali bleach.

This tendency is greatly enhanced in the presence of propane or similar diluent which serves to bring such oxygenated color bodies to the point of incipient precipitation and thereby greatly facilitates their removal by the alkali. Similar selective effects tend to increase the bleaching and removal of color bodies obtainable by contact with an adsorptive agent whereby the effectiveness of the adsorptive agent is very substantially increased, its life or refining capacity prolonged or increased, and whereby the desired bleach may be obtained at substantially lower contact temperatures than ordinarily employed. I also nd that, at reduced temperatures, propane is selective in its solvent power as regards low and high melting point constituents, whereby the precipitation of the latter from a chilled mixture is made morel selective and complete.

The low density and viscosity of the propaneoil mixture greatly facilitates all separative processes, 'such as the decanting and illtering processes illustrated in the drawing, and other separative-expedients which may be employed` if desired, such as separation by centrifuging which can be used instead of the settling vessels shown without departure from the vspirit of the invention. In addition, the greatly reduced viscosity of the mixture facilitates reactions between heterogeneous phases which are dependent upon diffusion to the interface, for example, the neutralizatlon of free fatty acids.by contacting the propane-oil mixture with aqueous alkali.

The optimum temperatures and propane-oil ratios will vary according to the character of the cil being treated and the desired character of theproducts, and cannot be given with exactitude. I usually prefer to commingle the diluent and crude oil at elevated temperatures, for example, by preheating the respective streams, in order to obtain a more homogeneous initial solution, although, with other more fluid oil, suchl preheating becomes unnecessary. The subsequent ref'lning steps may be carried out at various temperatures at, above, or below atmospheric temperature, depending upon the character vof? the oil and the refining procedure. The desumming operation may be carried out over a wide range of temperatures, although at atmospheric temperatures and below, the rejection is usually more complete than at somewhat more elevated temperatures. However, at considerably more elevated temperatures, for example around 150 F., the rejection of minor impurities is again quite complete.

The alkali-refining step can also be carried out over a wide range of temperatures, although, as a rule, I find that the. reaction is more rapid and the separation more complete at elevated temperatures. As a general rule, I find that temperatures in excess of 150 or 180 F. are rarely advisable and, usually, the desired refining can be obtained at substantially lower temperatures.

The step of clay refining may be conducted to advantage at elevated temperatures, for example, temperatures similar to those used in the alkali-refining step. In general, these temperatures will be well below the dehydration temperatures of the clay and I prefer, therefore, to use a clay which has been previously dehydrated to the desired reactivity.

The temperature to which the propane-oil mixture is chilled in the wintering process will depend upon the stearin content of the crude oil and the desired melting point of the wintered oil, and may he readily determined in practice to give the desired results. As a rule, such wintering operations will be carried out at sub-zero temperatures.

The volume ratio of propane to oil may vary over a very wide range, forexample, from onehalf to four or five, or more. I usually prefer to use several volumes of propane per volume of oil in precipitating the minor impurities, but the optimum ratio will vary according to the character of the crude oil, temperature of treatment, and other factors. If desired, the quantity of propane may be somewhat reduced in steps subsequent to degumming. Expedients may be provided, if desired, to change the propaneoil ratio between various of the refining steps, such an expedient comprising an evaporator and/or a propane addition line associated withthe transfer line between the refining units. It is usually sufficient, however, to maintain the same propane-oil ratio `throughout `the entire refining steps, for example, a ratio of one to three volumes of propane per volume of oil, until such time as the evaporative chilling is resorted to in the chilling equipment l5. Ii the removal of the higher melting point constituents is practiced as one of the earlier steps, then a sufficiently high propane-oil ratio should be employed initially to leave sufiicient propane in the filtrate to properly dilute the oil for the remaining steps, or, if desired, make-up propane may be added, suitablyA through the wash line leading to the filter. 1

The equipment should be closed throughout and constructed to withstand the vapor pressures of the diluent at the temperatures em- A l ployed. Various changes in the character of the equipment and procedural steps may be made, if desired. Forl example, in place of the decanters and filters, centrifuges adapted to operate under pressure may be very advantageously used as separating means for removing the precipitated minor impurities or foots from alkalirening and the like.` Instead o f the percolation tower for treating with clay, a continuous contact filtration method may be used in which a clay slurry is introduced into the propane-oil mixture and then removed therefrom by means of filters or centrifuges. Many other modifications of the process will lso be apparent to one skilled in the art. A

The process is, in general, applicable to glyceride oils and fats of animal and vegetable origin and, while it has been illustrated with particular reference to oils, it is likewise applicable to fats which are solid at Inormal temperatures, and I intend to term "fatty oil to cover such fats. Certain of the refining steps, for example, clay treatment and separation of higher melting point constituents in the presence of the preferred diluent, may be applied to the purification or separation of fatty acids.

It is to be understood that various modifications in apparatus and procedure may be made without departing from my invention as defined by the scope of the appended claims.

I claim as my invention:

1. The process of removing gummy' materials from crude fatty material containing the same which comprises the steps of mixing said crude fatty material with liquefied normally gaseous hydrocarbon to dissolve the fatty material and precipitate gummy material, and separating said precipitated gummy material from said fatty material, said steps being carried on in the presence of said hydrocarbon and under sufficient pressure to maintain said hydrocarbon in liquid form.

2. The process of removing gummy materials from crude fatty material containing the same, which comprises the steps of, mixing said crude fatty material with aliquefied normally gaseous hydrocarbon to dissolve the fatty material and` precipitate gummy material, separating the prev cipitated gummy material from said fatty matepresence of said hydrocarbon and under sufficient. pressure to maintain said hydrocarbon in liquidA form.

3. The process of refining crude fatty oils containing gummy materials and free fatty acids, which comprises the steps of, mixing said fatty oil with a liquefied normally gaseous hydrocarbon to dissolve said fatty oil and precipitate said gummy materials from said oil, separating the precipitated gummy material from said fatty material, thereafter mixing an aqueous neutralizing agent with said oil to neutralize said vfree fatty acids and precipitate soapstock, and separating said soapstock from said oil, said steps being carried on in the presence of said hydrocarbon and under suiiicient pressure to maintain said hydrocarbon in liquid for 4. The process of refining crude fatty oils containing gummy materials and free fatty acids, which comprises the steps of, mixing saidfatty oil with a liquefied normally gaseous hydrocarbon to dissolve said fatty oil and precipitate said gummy materials, separating said precipitated gummy materials from said oil, thereafter mixing an aqueous neutralizing agent with said oil to neutralize said free fatty acids and precipitate soapstock, separating saidsoapstock from said oil, thereafter adding a solid adsorbent to said oil and separating said. oil from said adsorbent and impurities adsorbed thereon, said steps being carried on in the presence of said hydrocarbon and under pressure sufficient to maintain said hydrocarbon in liquid form.

5. The process of refining crude fatty oils containing gummy materials and free -fatty acids, which comprises the steps of mixing said fatty oil with a liquefied normally gaseous hydrocarbon to dissolve said fatty oil and precipitate said gummy materials, lseparating said precipitated gummy materials from said oil, thereafter mixing an aqueous refining agent with said oil to precipitate foots, and separating said foots from said oil, said steps being carried on in the presence of said hydrocarbon and under sufficient pressure to maintain the said hydrocarbon in liquid form.

6. A process as defined in claim 1. in which the separation is effected within an elevated temperature range suiiiciently high to cause substantial rejection of the gummy material from the fatty material but at a temperature at which said hydrocarbon remains liquid at said pressure.

'7. A process as defined in claim 6, in which said elevated temperature range begins at about 150 F.

8. A process as in claim 6, in which the precipitation is assisted by the addition of a little water to hydrate impurities in the fatty material.

9. A process as defined in claim l, in which the crude fatty material and the liquefied normally gaseous hydrocarbon are subjected' to a temperature of around 150 F. to effect rejection of the gummy material and separation thereof from said fatty material.

10. A process as defined in claim 1, in which the separation is effected Within an elevated temperature range sufliciently high to cause substantial rejection of the gummy material from the fatty material but at a. temperature at which said hydrocarbon remains liquid at said pressure and in which at least several volumes of hydrocarbon are employed per unit volume of fatty material.

11. A process as defined in claim i, in which liquid form.

said steps are performed in the presence of a small amount of water.

12. A process as defined in claim 1, in which the separated gummy material comprises gums and oil. and including the step of subjecting the separated gummy material to further. fractionation while admixed with liquefied, normally gaseous hydrocarbon to recover oil therefrom.

13. A process as defined in claim 12, in rwhich the further fractionation is effected by contact with added hydrocarbon.

14. The process as defined in claim 1, in which the separation is effected within an elevated temperature range sufficiently high to cause substan.. tial rejection of the gummy material from a fatty material component but at a temperature at which said hydrocarbon remains liquid at said pressure and in which the hydrocarbon solution of degummed fatty material is subjected to further ractionation to reject a further fatty material component therefrom, said fractionation being conducted in the presence of at least a portion of said liquefied normally gaseous hydrocarbon.

15. The process as defined in claim 14, in which a stearine component is rejected from one of said fatty material components by chilling.

16. The process as defined in claim l, in which separation is effected at a temperature not substantially higher than atmospheric temperatures.

17. 'I'he process as dened in claim 16, in which precipitation is assisted by the addition of alittle water to hydrate impurities in the fatty material.

i8. The process as defined in claim 17, in which the ratio of liquefied hydrocarbon to fatty material is from about 1/2 to 4.

19. A process as defined inclaim l, in which the separated gummy material comprises gums and oil, and including the step of washing the separated gummy material with an additional quantity of liquefied normally gaseous hydrocarbon to recover oil from the separated gummy material, said. washing being effected under suilcient pressure to maintain said hydrocarbon in FREDERICK J. EWING.

No references cited. 

